Ankle boot



FIG. 1 is a perspective view of an ankle boot showing my new design;

FIG. 2 is a right side elevational view thereof, the left side being a mirror image; and

FIG. 3 is a front elevational view thereof.

The bottom of the ankle boot, not shown, is flat, plain and unornamented. 

The ornamental design for an ankle boot, substantially as shown and described. 